thanks for the answer. i'll give pbx a try .... but what i need it something that should be easy. the sip application should send a caller id .... that goes through the sip server to the receiver f the call. on my n82 and on other nokia phones (n95 for eg) ... in sip settings there is a field "public user name" .... here if i add "sip:+mymobile_no@nonoh.net" (i use nonoh) , when i make a sip call, the receiver of my call sees my mobile phone # .... not some strange no .... or private call ....